1. Field of the Invention
This invention relates to apparatus for binding pads of perforated sheets to book form, such as, for example, notebooks, calendars, instruction manuals and the like, with wire binding elements.
2. Description of the Prior Art
The wire binding elements for use with such apparatus are formed from a length of wire which is bent to form a series of curved, hair-pin shaped prongs. Each prong has a closed end, or "point", an open end, or "root", and a curved wall therebetween. The curvature of the prongs is such that the element has the appearance of an open-sided cylinder with a substantially C-shaped cross-section. Such binding elements will hereinafter be described as "binding elements of the type described".
To bind pads of perforated sheets to book form, a binding element of the type described is cut to a predetermined length and a pad of perforated sheets is moved relative to the binding element, or vice versa, so that the points of the binding element pass through the perforations. The binding element is then closed to ring shape by bringing its points into the vicinity of its roots thereby binding the pads.
The step of aligning the pad of perforated sheets with the binding element and moving the pad so that the points of the binding elements pass through the perforations is commonly carried out automatically, see for example our prior British Patent No. 2213769. However, apparatus which can carry out this step reliably is complicated and expensive. Furthermore, it is often a requirement to bind pads of differing sizes with binding elements of varying sizes and apparatus which can meet this requirement is yet more complicated and expensive.